Molecular Flashcards

1
Q

Stats

A

3 billion base pairs
22,000 Genes
1.5% encodes for genes
AT has 2 bonds
GC has 3 bonds

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2
Q

Mutation types

A

Silent - not a problem because more than one codon codes for amino acid (redundant)

Missense - wrong amino acid called for, may or may not be a problem

Nonsense - premature stop codon

Insertion

Deletion

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3
Q

Codons

A

All proteins start with AUG > Methionine

UAA, UAG, UGA are stop codons

5’ cap and poly A tail is added before leaving nucleus

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4
Q

Inheritance

A
  • Autosomal Dominant -
    • often are neurologic, connective tissue (Seizures,Huntingtons, Marfans, Achondroplasia)
    • vertical transmission
  • Autosomal Recessive -
    • often enzymes
    • most common, usually no family history except horizontal
    • cystic fibrosis, sickle cell disease, phenylketonuria.
    • both parents are carriers
  • X-linked Recessive
    • No male to male transmission
    • fabry dz, muscular dystrophy, hemophilia a/b, red-green color blindness
  • X-linked Dominant
    • very rare
    • Rett syndrome, Incontinentia pigmenti
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5
Q

Mitochondria Inheritance

A
  • two to three symptoms with no connection think about mitochondrial
  • circular dna
  • 37 genes, all related to oxidative phophyrylation
  • still uses many nuclear DNA for these pathways
  • Maternal inheritance
  • can have heteroplasia where some mitochondria have a mutation and others do not
  • Examples
    • Kearns Sayre, Leber Heriditary Optic Neuropathy, MELAS, MERRF
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6
Q

Genomic Imprinting

A
  • Only the mother or father’s gene is not expressed
  • methyl groups prevent one from being transcribed
    • sometimes need methylation studies to figure things out
  • most of one of the X chromosome or inactivated in females
  • Examples
    • Angelman: UEB3A gene only active when inherited from mother
  • Chromosome 15, deletion on 15q mutation can also lead to PW
    • Prader Willi: SNP gene only active when inherited from the father (prader no father)
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7
Q

Triple Repeat Disorders

A
  • Autosomal Dominant
    • Huntington Chorea : CAG coding exon
    • Myotonic Dystrophy (DM1): CTG 3’ end
    • SCA (Spinocerebellar ataxia)
  • Autosomal recessive
    • Friedrich Ataxia: GAA intron
  • X-Linked
    • Fragile X (expansion 5’, CGG, increased expression in oogenesis)
  • often not identified in NGS but can be identified in whole genome studies
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8
Q

Cell Cycle Review

A
  • Checkpoints in the cell cycle
    • Proper cell growth (G1)
    • Is DNA replication correct? (G2)
    • Mismatch repair
    • May not pass, no more replication
    • Cancer cells might skip checkpoints
      • leads to uncontrolled proliferation
        *
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9
Q

Blotting Techniques

A
  • Southern (DNA)
  • Northern (RNA)
  • Western (Protein)
  • Disadvantages
    • needs lots of blood (no application)
    • time consuming
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